terça-feira, 24 de janeiro de 2012

People view genetically influenced outcomes as inescapable and predestined. They tend to forget the important influences of free will and environment. Furthermore, they often view the genetically influenced outcome as natural, and may assume the “naturalistic fallacy,” where ethical properties (i.e., the moral “ought” or “good”) are erroneously presumed to flow from natural properties (i.e., the “is,” or mere fact of existing). A recent analysis by Dar-Nimrod and Heine (2011a) offer cautions that pertain to genetically influenced conditions including homosexuality.

Reviewed by Christopher H. Rosik, Ph.D.

A recent article published in the highly esteemed journal Psychological Bulletin (Dar-Nimrod & Heine, 2011a) addressed the timely subject of the psychological effects of considering genetic foundations to human nature. The article and invited responses considered the effects such genetic explanations have for a number of areas, which are worth reading on their own right, but this review will of necessity focus on the authors’ discussion of the genetic foundations of sexual orientation.

Psychological Essentialism

The authors begin their discussion by asserting that human beings tend to “essentialize” certain entities that they encounter. That is, they perceive “natural” categories to living organisms that make them what they are. The authors note, “People demonstrate psychological essentialism when they perceive an elementary nature or essence, which is underlying, deep, and unobserved, that causes natural entities to be what they are by generating the apparent shared characteristics of the members of a particular category” (p. 801). People rely on presumed essences and assume essentialist judgments when they attempt to understand the behavior of social groups. Dar-Nimrod and Heine postulate that psychological essentialism is likely to be a universal aspect of human functioning.

Although the essence of any category is not observable, people use “essence placeholders” to overcome the abstractness of the essence. The authors contend “…that ‘genes’ (or at least the way that most laypeople conceive of genes) often serve as the placeholder for this imagined essence, and this has important implications regarding how individuals respond when they encounter genetic information about people” (p. 801). The defining elements of psychological essentialism (namely viewing a characteristic as immutable, fundamental, homogenous, discrete, and natural) are similar to the common lay perception of genes.

Genetic Essentialism Defined

The authors offer four consequences of genetic essentialism:

It may lead people to view outcomes as immutable and determined, unfolding according to some fixed underlying genetic process that are assumed to be largely independent of environmental influences and beyond individuals’ control. Consequently, people view genetically influenced outcomes as inescapable and predestined.

It may lead people to view the relevant genes as entailing the fundamental cause of the condition. The perception of a genetic foundation thus leads people to devalue the role of environmental and experiential factors. It may lead to people viewing groups that share a genetic foundation as being homogenous and discrete. All members of a group that share a genetic essence have the potential to possess the associated condition and that condition is not expected to be observed in those who do not share the underlying genetic foundation. It causes people to view the outcome as natural, and, in some domains, this may prompt the naturalistic fallacy, which results in the associated outcomes being perceived as more morally acceptable. Here ethical properties (i.e., the moral “ought” or “good”) are erroneously derived from resumed natural properties (i.e., the natural “is” or fact of existing).

The authors observe that the naturalistic fallacy has benefited gays and lesbians but worked against criminals and the obese, since this fallacy emerges most strongly when outcomes are associated with behaviors that are seen as voluntary. Thus, perceiving homosexuality as natural leads to greater acceptance of same-sex behavior, while the opposite is true for criminal behavior or obesity.

Overall, these four biases lead people to attend more to genetic causes of a condition at the expense of considering environment, experience, or gene-environment interactions. Thus, genetic essentialist biases likely result in people giving more weight to genetic contributions than is justified.

Strong and Weak Genetic Explanations

Dar-Nimrod and Heine assert that genetic essentialism reflects a biased and often undesirable response to understanding genetic information. They describe “strong genetic explanations” as valid when genes influence phenotypes through major biochemical pathways that can be measured and understood, as is the cases for monogenic diseases such as Huntington’s disease or cystic fibrosis. However, since genotype-phenotype relationships are usually complex, it has to be kept in mind that monogenic diseases account for only about 2% of genetic-based diseases.

On the other hand, the authors indicate that, “Much of the ways that genes relate to human conditions can be described as weak genetic explanations” (p. 802). Here the condition has a genetic influence or basis (i.e., heritability > 0) yet the mechanisms that transmit it are mostly unknown or are unknowable. Almost all human behaviors are heritable in this manner, including voting behavior, cigarette smoking, and divorce. But since the nature-nurture interaction is typically complex for human phenomena and since these complexities are difficult to communicate and understand, all genetic explanations are viewed by many people as being strong genetic explanations.

Genetic Essentialism and Sexual Orientation

The authors examine the subject of sexual orientation as an example of how a political debate can hinge on the proposed existence of relevant genes. They discuss Hamer, et al.’s (1993) claim to have found a genetic marker (Xq28) that partly accounted for male homosexuality. They observe that the public reaction to this study provides a case study in genetic essentialism. The study led to media responses proclaiming a lack of choice in adopting a homosexual lifestyle as well as eugenics concerns such as elective abortions for “suspected” fetuses. Dar-Nimrod Heine observe,

Both reactions underscore how an immutable causal relationship between genes and homosexuality was perceived. The same kind of essentialist reactions did not follow, for example, psychoanalytic propositions that overbearing mothers and detached, cold fathers may be responsible for homosexual tendencies, although infants’ conscious control over these kinds of parental behaviors is arguably no greater than their control over their genes. Again, this is evidence that genetic arguments lead to qualitatively different reactions than environmental ones (p. 806).

The authors also note the connection between perceived genetic origin and reduced prejudice toward homosexuals. They comment that, “This relationship between a perceived genetic foundation and tolerance toward homosexuals demonstrates how genetic essentialism can lead to the naturalistic fallacy in some domains….Apparently, behaviors with moral implications lose their moral force if people view those behaviors as beyond the individual’s volition” (p. 806). While a reduction of negative evaluations of gay and lesbian persons is a potentially positive feature of genetic essentialism, the authors also sound a cautionary note since political contexts tend to be dynamic: “Given potential scientific advances (e.g., identification of genetic markers that may relate to homosexuality) or a change in political climate, the association that currently acts as a positive moderator of prejudice toward homosexuals could one day be used as grounds for eugenic practices” (p. 806).

Although the expression of genes for most human traits and behaviors—including those associated with homosexuality–is dependent on the presence of certain environmental variables and interactions with other genes, genetic arguments activate people’s essentialist biases. This, in turn, can provide them with seemingly unassailable materialistic explanations for why people act in the ways that they do.

Genetic Essentialism and the Media

The media is singled out by Dar-Nimrod and Heine for contributing to the spread of genetic essentialism, although they also lay some blame at the feet of the researchers themselves. As far as the media is concerned, the authors offer several reasons why the media are complicit in making genes appear to play a more central role than the data actually suggest. Research findings that portray genes as a cause of behaviors often receive far more coverage than compared with later disconfirmations. In addition, the media consistently provide an overly simplified picture of genetic research, dubbed the “one gene—one disease” (OGOD) concept, where a one-to-one deterministic relationship between a specific gene and a specific trait is offered (i.e., a strong genetic explanation). Another example not mentioned by the authors may be the media’s propensity to equate opponents of same-sex marriage to those who opposed mixed race marriage. Equating the etiologically complex phenomenon of homosexuality with the genetically determined trait of race very effectively serves to evoke essentialist biases.

Researchers, who are competing for media attention and grant funding, can also contribute to genetic essentialism in communicating about their work in ways that resonate with people’s essentialist biases (e.g., suggesting OGOD relationships or affording a sense of agency to genes by describing them as “selfish” or “wanting”). The result of these portrayals, according to the authors, is that “…people who gain their knowledge of genetics largely through the media are likely to conceive of genetic influences in overly deterministic, immutable, and ultimately erroneous ways” (p. 812).

By way of conclusions, Dar-Nimrod and Heine assert that in a variety of domains, including sexual orientation, attributions go beyond the scientific evidence, with weak genetic explanations being interpreted as strong genetic explanations. This is the unfortunate legacy of genetic essentialism.

Biogenetic and Neuroessentialism

The first response to Dar-Nimrod and Heine came from Haslam (2011), who generally approved of the genetic essentialism treatise yet wanted to extend it to the biological and neurological realms. Haslam examined the relationship of stigma to such essentialism in mental disorders and drew three conclusions:

Biogenetic explanations are generally associated with greater desired social distance from people with such disorders.

The only dimension of stigma that biogenetic explanations consistently reduce is perceived blame and personal responsibility. However, explanations that diminish the perceived personal responsibility of affected persons may have the unfortunate side effect of leaving them passive in the face of their own recovery.

These mixed effects of biogentic explanation on stigma make sense in light of psychological essentialism.

Expanding on his third point, Haslam observes that, “Explanations that draw deep distinctions between kinds of people would be expected to promote social distance, explanations that invoke unchanging identities would be expected to yield pessimism about change, and explanations that refer to causes that are beyond personal control would be expected to attenuate blame but amplify fears of uncontrollable behavior” (p. 821). While Haslam does not directly address sexual orientation in this context, his discussion does raise interesting questions about the extent to which the employment of strong genetic and biological explanations might promote social distance, create heightened pessimism regarding the modification of same-sex attractions, and suggest the inevitability of certain homosexual sexual practices.

Genetics and Human Agency

In the second response to the featured article, Turkheimer (2011) suggests that genetic essentialism has a counterpoint in naïve environmentalism, whereby the theoretical challenges of behavioral genetics are basically ignored. “Psychoanalysts were wrong to think that overbearing mothers made their children gay, and genetic essentialists were wrong about gay genes and similar nonsense,” Turkheimer observes, “but what is the right way to think about genetic influences on sexual orientation?” (p. 825). He then asserts that the preferred way to think about this is not in terms of heritability, because contrary to common wisdom, traits do not have heritabilities because heritability depends on the population in which it is measured. “No matter how heritable height may be in some particularly time and place,” notes the author by way of example, “neither height in a single individual nor differences in height among individuals can develop without an environment.”

Instead of heritability, then, Turkheimer looks to the language of a typical biometric analysis of a trait, such as found in twin studies. In such analyses, heritability is contrasted with two environmental components attributable to the shared variance and the nonshared variance. The shared component is comprised of environmental forces that make children in the same family more alike. By contrast, the nonshared environment comprises the nongenetic reasons that cause siblings raised in the same family to be different. It is the only reason identical twins raised in the same family have any differences at all. As such, the nonshared environment is the most important component for understanding the personal and ethical consequences of behavior genetics.

Turkheimer indicates there are two reasons why identical twins raised in the same family do not have identical outcomes. One is measurement error. The other, more intriguing reason “…is the self-determinative ability of humans to chart a course for their own lives, constrained but not determined by the genes, family, and culture, and in response to the vagaries of environmental experience with which they are presented. The nonshared environment, in a phrase, is free will” (p. 826).

The nonshared environment addresses what is at stake when we are concerned about whether people are able to control their own weight or choose their sexual orientation. Turkheimer presents the nonshared environment proportions (NEP) for the traits examined by Dar-Nimrod and Heine (2011a) and orders them in terms of their controllability and moral relevance, as displayed below.

Trait NEP

Height .1

Weight .3

Adult intelligence .2

Personality .6

Schizophrenia .15

Depression .6

Criminality .4

Sexual orientation .5

According to Turkheimer, we have a particular concern for the genetics of behavior, because behavior genetics is experienced genetics, and the interaction of genetics with human agency. While we are free to become what we want, doing so will take more effort for some traits than for others and will require a Herculean effort for the most ingrained. As seen in the table above, sexual orientation change generally appears to take somewhat more effort than the achievement of change in personality or depression and less effort than for reducing criminality or weight. Thus the comparative nonshared variance statistics suggest that while change in same-sex attractions is possible, it is by no means a simple or easy process. For Turkheimer, the NEP serves to prevent coarse and absolute claims about people either “having a choice” or being “hard wired” for their traits.

Concluding Rejoinder

The article series concludes with a rejoinder by Dar-Nimrod and Heine (2011b). The authors indicate that they agree with Haslam that biochemical substances and neurological mechanisms can also serve as effective primes for essentialist thinking. Extreme nature and nurture positions have a magnetic draw and tend to overwhelm more nuanced thinking. Dar-Nimrod and Heine view the interaction of nature and nurture as the most scientifically defensible explanation for human behavior, whereby genes are relevant to human behavior but do not determine it. This has implications for determining the morality of behavior, presumably including sexual behavior:

As there are no known complex human behaviors in which genetics render the actor unable to resist performing a behavior, we contend that genetic etiological accounts should not serve as the basis for moral evaluations. Genes provide one source of influence (depending upon how those genes are expressed in interaction with other genes and experiences and following a developmental trajectory), but there are many other sources of influence at play, making the role of genes in producing any complex behaviors far from deterministic. Furthermore, the amount of influence that genes have on behaviors is considerably smaller than one might think. (p. 831)

Dar-Nimrod and Heine do believe that genetic essentialist biases have greater potency than environmental essentialist biases or even interactionist accounts, since the former are much more likely to be perceived as offering an underlying, materialistic, immutable, and fundamental cause of an individual’s nature.

Finally, the authors agree with Turkheimer’s criticism of how heritability estimates have been misused. In addition, they offer for consideration another way heritability estimates have been misinterpreted. They note that in the heritability research one large component of environmental influence is never taking into account people’s cultural background. Experimental designs are not capable of accounting for the role of different cultural backgrounds, which results in a substantial restriction of range problem in making estimates. This means that the role of environmental influence on these behaviors is going to be grossly underestimated and the estimates of heritability overestimated. Heritability estimates therefore are most meaningful when their relative size is contrasted between characteristics assessed in the same samples and contexts.

This would appear to have serious consequences for understanding the degree of heritability of sexual orientation, since we have little if any such research coming out of non-Western cultures to compare with what has been reported in the West. Researchers may currently and erroneously assume genetic heritability estimates are universally valid when in fact this is far from the truth. These estimates may well be far smaller than we think.

In summary, Dar-Nimrod and Heine, as well as their respondents, have provided a valuable service by raising awareness of the causes and effects of genetic essentialism and some ramifications of it for our thinking about sexual orientation. It is difficult to do justice in a brief review to the depth of insights and thought provoking analysis that are contained within these pages. Interested readers who wish to dig into the original sources will not be disappointed with their investment of time. Portrayals of the origin of homosexuality in the media as well as in some of the relevant science appears to provide potent examples of genetic essentialism (and perhaps biochemical essentialism too). We would be wise to keep the lessons of Dar-Nimrod and Heine’s analysis in mind as we consider the causes of homosexuality and the claims of its immutability.